1. Field of the Invention
This invention relates to traffic signals.
2. Description of the Prior Art
The conventional traffic signal device contains an incandescent lamp supported in the appropriate place in a reflection containment to provide generally parallel beams of light to illuminate the visible display of the traffic signal device. The incandescent lamps in conventional traffic signal devices usually consume between 69 and 135 watts of power, depending upon how much brightness is required to overcome ambient light conditions around the signal device. The life expectancy of these bulbs is generally in the area of 8,000 hours of burning time. The power demands of these incandescent lamps result in cost to the entity responsible for operation of the signal, and the lifetime of the lamp involves additional cost due to the need for work crews to replace the lamps relatively frequently. Also, the cost of manufacture of the signal is greater due to the cost of hinges, fasteners, and gaskets necessary to provide ready access to the interior for lamp replacement.
An additional problem with conventional traffic devices commonly occurs in a number of specific signal applications, particularly in pedestrian WALK/DON'T WALK signal devices. The usual arrangement of pedestrian signal devices is to have two displays, one display having a symbol indicating WALK, and the other display having a symbol indicating DON'T WALK. When sunlight shines on the signal displays, it will frequently produce what is known as phantom image. In a phantom image, the sunlight reflects off the display surface, which is usually reflective prismatic material similar to that used in automobile tail lights, and gives the false impression that the display is illuminated, when in fact it is not.
Reference is made to U.S. Pat. No. 4,308,572 which discloses the use of diodes in clothing or on fabric or other displays. However, none of these disclosures relate to traffic signals which have been made and tested by me to obtain a high resolution signal far superior to those presently in use and which can be easily seen in various weather conditions.
Signals have been provided with shades or hoods in an attempt to overcome this problem, but with only limited success, since it is very difficult to exclude sunlight from the display while providing visibility of the display to traffic.